Carburetor



June 1, 1937.

CARBURETOR Filed Deo. 5, 1955 choke Patented June 1, 1937 UNITED STATES PATENT oFFlcE 11 Claims.

This invention relates to an improvement in carburetors which has for one of its objects to maintain a considerable vacuum under all operating conditions in and around the fuel nozzle and in the mixing chamber for the purpose of insuring and maintaining complete atomization of the fuel from the time it enters the mixing chamber until it reaches the engine cylinder. At the same time, the fuel which is supplied from the fuel nozzle should be metered in order to insure a mixture of the proper proportions at different positions of the throttle. By this construction, it is possible to supply gasolene through the main nozzle both for idling and for part throttle operation and to thereby eliminate the expensive means for by-passing the fuel around the throttle, which is common practice in plain tube carburetors.

In addition to the main throttle valve, llocated on the engine side of the fuel nozzle, the invention involves a second valve, which is unbalanced, on the opposite side of the fuel nozzle. This second valve restricts the flow of air for idling and for part throttle operation, but not for full power. It may be said, therefore, that the inventlon presents the characteristics of an air valve carburetor for part throttle operation and of a plain tube carburetor for full power.

In the accompanying drawing- Fig. 1 is a, vertical section taken centrally of the mixing chamber and fuel bowl ofV a carburetor constructed in accordance with the invention.

Fig. 2 is a partial section, similar to Fig. 1, showing a modified form of the invention.

The carburetor as shown is of the down draft type, although the invention is not limited to that type of construction. It comprises a mixing chamber 5 formed with a venturi 6, adjacent to which Ais a fuel bowl l of well known construction, having a fuel inlet pipe 8 with a valve 9 controlled by a float I 0. From the bottom of the bowl l, a fuel passageway II4 leads to a well I2, from which fuel is delivered to a nozzle I3 located within the venturi 6. -A throttle valve I4, at the lower end of the mixing chamber 5, is provided with an arm I 5, which is actuated in the usual manner through the medium of a rod I6 to open or close the throttle.

Theinner end of the arm I5 is extended beyond the axis of the throttle valve, as at l 1, and is there connected to a rod I 8, which telescopes freely into the end of a rod I9. The other end of the rod I9 is connected to the arm 20 of a second valve 2l, which is unbalanced, so that the air flow and the suction-oi the engine tend to open it when the throttle is partly or wholly open.

(ci. 2in-49) The outer end of the arm is connected by a link 22 to a piston 23, which is reciprocable in a dash pot 24, the latter having a bleed 25 opening to the atmosphere to permit the valve 2| under the influence of suction and air ow to slowly follow the opening movement of the valve I4.

A by-pass bleed opening 26 is normally closed by a needle Valve 2l, which is held by`a lever 28 pivotally mounted at 23 and acted on by the tension of a coil spring 30. In other words, the valve 2I lags behind the valve I4, temporarily enriching the mixture for part throttle acceleration and thereby dispensing with the need for an accelerating pump. When the throttle valve I4 is opened wide, a cam 3l on the valve axis strikes the lever 28 and positively opens the needle valve 2l against the resistance of the spring 30, thereby permitting the dash pot 24 to vent quickly and preventing the fuel mixture from being too rich on wide open throttle acceleration.

The dash pot 24 also has an air inlet 32 controlled by a relief valve 33, which permits the dash pot to be filled quickly with air as the valve 2| closes with the valve I4.

The amount of fuel supplied to the nozzle I3 is determined by a metering pin 34, which is connected to the arm I5 by a link 35 and which has one side flattened, as at 36, so as to supply an increasing amount of fuel as the throttle is opened. The closing of valve 2l simultaneously with the valve I4 is positively eected by a nut 3l on the rod I8, which engages the lower end of the rod I9. The gasolene supply for idling is determined by the position of the metering pin 34, but this supply may be varied by adjusting the nut 3l, thereby determining the idling position of the valve 2l and the degree of vacuum at the nozzle when the engine is idling.

For choking the engine, an arm 38, loosely mounted on the axis of the valve 2l, is provided with an arcuate slot 39 which receives a pin 40 secured to the arm 20. A choke rod 4l is connected to the arm 38 and, when moved in the direction of the arrow, positively holds the valve 2l closed when the valve I4 is opened, thereby restricting the lsupply of air to the fuel mixture.

In the modification shown in Fig. 2, the dash pot 24 is filled with liquid instead of air. That is, it is connected with thevbowl 'l by a bleed 45. A larger vent passageway 46 is normally closed by a needle valve 41, acted upon by a spring 43. The needle valve 41, however, is connected by a lever 49 to a rod 50 which is looped around-the rod I8. When the throttle valve I4 is opened wide, the nut 31 engages the loop on the rod I8 and opens the needle valve, thus permitting the dash pot to vent quickly. Upon closing the valves I4 and 2|, the relief valve 5I opens, so that the dash pot is quickly relled through the passage- 5 way 52.

From the foregoing description, it will be understood that the dash pot will always resist the opening of the air inlet valve 2| whenever the throttle valve I6 is partially opened, thereby caus- 10 ing the valve 2| to lag behind. This enriches the mixture during acceleration, by reason of the increased vacuum or suction, as well as insuring complete atomization. It also prevents overcharging of the engine at low speed when the throttle is opened suddenly, but the air flow is not materially restricted when the throttle is wide open for full power and this prevents the mixture from becoming too rich at such time.

It is to be understood that the invention is not limited to the embodiments 'herein shown and described, but embraces such other modifications as may fall within the scope of the appended claims.

I claim:

1. In a carburetor, a mixing chamber, a throttle valve on the engine side thereof, an air inlet with an unbalanced valve' therein adapted to be opened only by the pressure of the air passing I through said inlet, said chamber being formed with a venturi between the two valves, a fuel inlet at the narrowest point in the venturi, means for increasing the capacity of the fuel inlet as the throttle valve is opened, means to limit the possible opening of the air inlet valve in proportion to the opening of the throttle valve, and means to temporarily resist the opening of the air inlet valve when the throttle valve is opened quickly.

2. In a carburetor, a mixing chamber, a throttle valve on the engine side thereof, an air inlet with an unbalanced valve therein tending to open under the inuence of air ow or mixing chamber suction, said chamber being formed with a venturi between the two valves, a fuel inlet at the narrowest point in the venturi, means for increasing the capacity of the fuel inlet as the throttle valve is opened, means to limit the possible opening of the air inlet valve in proportion to the opening of the throttle valve, and a dash pot connected with the air inlet valve to retard its opening movement when the throttle valve is opened quickly.

3. In a carburetor, a mixing chamber with a throttle valve on the engine side thereof and an unbalanced air inlet valve at the other side adapted to be opened only by air flow through said inlet, said chamber being formed with a venturi between the two valves, a fuel inlet at the narrowest point of the venturi, a metering pin for the fuel supply to said inlet, means connected with the throttle Valve and controlling the metering pin to increase the capacity of the fuel inlet 'as the throttle is opened, a dash pot connected to the air inlet valve to offer temporary resistance to the opening thereof, and a lost motion connection between the throttle and the air inlet valve positively limiting the opening of the latter in proportion to the throttle opening.

4. In a carburetor, a mixing chamber with a throttle valve on the engine side thereof and an unbalanced air inlet valve onthe other side, said chamber being formed with a venturi between the two valves, a fuel inlet at the narrowest point of the venturi, a metering pin for the fuel supply to said in1et,means connected with the throttle valve and controlling the metering pin to increase the capacity of the fuel inlet as the throttle is opened, a dash pot connected to the air inlet valve to retard its opening, and means actuated by the closing movement of the throttle constituting the sole means normally tending to close the air inlet valve and for limiting its opening in proportion to the throttle opening, suction and air flow past the unbalanced air inlet valve constituting the sole means for opening the same.

5. In a carburetor, a mixing chamber having fuel and air inlets, a throttle valve, a valve for the air inlet adapted to be opened by air ow into the mixing chamber, means to limit the possible opening of the air inlet Valve in proportion to the opening of the throttle valve, a. dash pot connected to the air inlet valve and constituting the sole means to normally oppose its opening tothe limit indicated, said dash pot having a comparatively small constantly open vent and a second vent normally closed, and means to open the second vent when the throttle valve is opened wide or nearly so.

6. In a carburetor, a mixing chamber having fuel and air inlets, a throttle valve, a valve for the air inlet adapted to be opened by air iiow through said inlet, means to limit the possible opening of the air inlet valve in proportion to the opening of the throttle valve, a dash pot connected to the air inlet valve and constituting the sole means to normally oppose its opening to the limit indicated, means for metering the fiow of fuel through the fuel inlet in synchronism with the opening of said throttle valve, said dash pot having a comparatively small constantly open vent and a second vent normally closed, and

means to open the second vent when the throttle valve is opened wide or nearly lso.

7. In a carburetor, a mixing chamber, a throttle valve on the engine side thereof, an air inlet with an unbalanced valve therein tending to open under the influence of air flow into said chamber, means to limit the possible opening of the y air inlet valve in proportion to the opening of the throttle valve, said chamber being formed with a venturi between the two valves, a fuel inlet at the narrowest point of the venturi, means for increasing the capacity of the fuel inlet as the throttle valve is opened, a dash pot connected with the air inlet valve and constituting the sole means to normally oppose its opening movement when the throttle valve is opened quickly, said dash pot having a comparatively small constantly open vent and a second vent normally closed, and means to open the second vent when the throttle is opened wide or nearly so. l

8. In a carburetor, a mixing chamber with a throttle valve on the engine side thereof and an unbalanced air inlet valve at the other side adapted to be opened by air flow, said chamber being formed with a venturi between the two valves, a fuel inlet at the narrowest point of the venturi, a metering pin for the fuel supply to said inlet, means connected with the throttle valve and controlling the metering pin to increase the capacity of the fuel inlet as the throttle is opened, a dash pot connected to the air -inlet valve to retard the opening thereof, a lost motion connection between the throttle and the air inlet valve positively limiting the opening of the latter in proportion to the throttle opening, said dash pot having a constantly open vent and a second vent normally closed, and means to open the second vent only when the throttle is opened wide or nearly so.

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9. In a carburetor, a mixing chamber with a throttle valve on the engine side thereof and an unbalanced air inlet valve on the other side, said chamber being formed with a venturi between the two valves, a fuel inlet at the narrowest point of the venturi, a metering pin for the fuel supply to said inlet, means connected with the throttle valve and controlling the metering pin to increase the capacity of the fuel inlet as the throttle is opened, a dash pot connected to the air inlet valve to retard its opening, means actu* ated by the closing movement of the throttle constituting the sole means normally tending to close the air inlet valve and for limiting its opening in proportion to the throttle opening, suotion and air ilow past the unbalanced air inlet valve constituting the sole means for opening the same, said dash pot having a constantly open vent and a second vent normally closed, and means to open the second vent only when the throttle is opened wide or nearly so.

10. In a carburetor, a mixing chamber, a throttle valve on the engine side thereof, an unbalanced air inlet valve between the mixing chamber and the atmosphere, a lost motion connection between the two valves having in itself no effect on the opening of the unbalanced valve when the throttle Valve is opening but positively closing the unbalanced valve in synchronism with the throttle valve as the latter is closed, the air flow past the unbalanced valve constituting the sole means for opening it, and a dash pot constituting the 4sole means normally resisting the opening of the unbalanced valve when the throttle valve is opened.

11. In a carburetor for internal combustion engines, a mixing chamber having fuel and air inlets, a throttle valve on the engine side of said chamber, a metering pin connected With the throttle valve to increase the capacity of the fuel inlet with the opening of the throttle, an unbalanced valve for the air inlet, a lost motion connection between the throttle valve and the unbalanced -valve positively closing the latter as the throttle is closed but releasing it to the influence of the air ow as the throttleis opened, an-d a dash pot retarding the action of the unbalanced valve in following the opening movement of the throttle valve.

MARION MALLORY. 

